This invention relates to lever type door knobs, and more particularly to an adapter for retrofitting conventional door knobs with a lever.
Because of the desire to assist the handicapped in their access to public facilities, efforts are being exerted through laws and regulations to make such access a reality by requiring the construction of ramps, elevators, toilet facilities, etc. suitable for use by the handicapped. Included among these requirements is that door knobs be of the lever type so that a door may be opened by a person having less manual dexterity than is required to turn a conventional round knob. Unfortunately, the cost of replacing each round door knob with a lever is much greater than might be expected because not only must the round knob be replaced, but also the inner mechanism of the door lock. The inner mechanism must be modified because the turning force produced by the off-axis weight distribution of the handle portion causes the lock mechanism designed for a round knob to either completely or partially open the door lock because the spring which holds the tongue of the lock in the extended position (the locking position) is too weak to withstand the turning force produced by the lever. Therefore, for retrofitting a round knob type of door latch, not only must the knob be replaced by a lever, but also the spring must be replaced by a stiffer spring or if that is not possible, the latch mechanism must also be replaced. The cost of replacing round knob combination passage and lock assemblies with a lever handle configuration currently requires the replacement of a passage latch which has stiffer springs to counteract the off axis lever weight and the installation of a separate mortise lock.